Water pollution degrades surface waters making them unsafe for drinking, fishing, swimming, and other activities. As authorized by the Clean Water Act, the National Pollutant Discharge Elimination System (NPDES) permit program controls water pollution by regulating point sources that discharge pollutants into waters of the United States. Point sources are discrete conveyances such as pipes or man-made ditches. Individual homes that are connected to a municipal system, use a septic system, or do not have a surface discharge do not need an NPDES permit; however, industrial, municipal, and other facilities must obtain permits if their discharges go directly into surface waters. In most cases, the NPDES permit program is administered by authorized states. Since its introduction, the NPDES permit program is responsible for significant improvements to our Nation's water quality.
The NPDES storm water program called for implementation in two phases; Phase I addressed the most significant sources of pollution in storm water runoff. Phase II addresses other sources to protect water quality. Construction sites that disturb one acre or more of land are required to have coverage under the NPDES general permit for storm water discharges from construction site activities.
The United States Environmental Protection Agency has set forth guidelines for municipalities in the NPDES Phase II Storm Water Rule that outlines best management practices (BMPs) for limiting pollutants in storm water drainage systems. Drainage inlet protection devices help to satisfy the following NPDES Phase II control measures: 1) Construction site storm water runoff control; 2) Post-construction storm water management in new development and redevelopment; and 3) Pollution prevention and good housekeeping for municipal operations.
Inlet protection devices have been developed to address the concerns of construction site storm water runoff. Previous inlet protectors may be composed of injection molded plastic housings with a fixed size and shape and particular dimensions. However, fixed dimension plastic inlet protection devices are expensive to tool and can be overly complex to install and maintain.
Other types of inlet protection devices, such as the Illinois Department of Transportation (IDOT) approved Inlet Filter, are comprised of welded steel angles and channels designed to fit specific drainage structures with fixed dimensions. The steel frames also support a sediment bag which filters the storm water. Various geotextile sediment bag materials, oil absorbent pouches, and other filtration devices can be utilized with the IDOT Inlet Filter. The sediment bag hangs below grade catching storm water runoff and debris as it is washed into the drainage structure.
There are hundreds of different sized curb and catch basin inlets in use throughout the world. There are two primary shapes for curb and catch basin inlets: rectangular and circular. Fixed dimension inlet filters are manufactured to fit one specific size of inlet basin. Furthermore, the fabrication of the welded steel frames is tedious and labor intensive resulting in higher cost levels of finished goods, long lead times, and elevated prices. Contractors typically order and stock fixed dimension size inlet filters relating to specific drainage make and model numbers. Contractors that come into contact with a large number of different types of inlet castings may need to stock a large inventory of inlet filters of varying shapes and dimensions. Additionally, pre-existing roadwork may contain inlets of unknown origin and nonstandard dimensions.
Still other types of inlet protection devices are comprised of geotextile fabric sediment bags that are attached to an existing inlet. For example, these sediment bags may be suspended from straps or chains, which are wrapped around or attached to an inlet grate. Some sediment bags have slots adapted to contain pieces of re-bar used to hold down sides of the sediment bag on the outside of the inlet grates, above grade. Other types of sediment bag inlet protection devices require that the inlet grate be inserted into a geotextile envelope preventing sediment from entering at the surface. These “fabric-only” style sediment bag inlet protectors are more difficult to install and maintain than inlet protectors utilizing a “drop-in” rigid frame supporting a sediment bag.
The foregoing summary, as well as the following detailed description of certain embodiments of the present invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, certain embodiments are shown in the drawings. It should be understood, however, that the present invention is not limited to the arrangements and instrumentality shown in the attached drawings.